Plate-type heat exchanger



OCta 8,

J. E. POTTHARST, JR

PLATE-TYPE HEAT EXCHANGER 3 Sheets-Sheet 1 Filed June 21, 1967 D/J 7.//V

.. c/Ofifi Z, Pod 40AM, J).

INVENTOR.

ATTORNEY 1968 J. E POTTHARST, JR 3,404,733v

I PLATE-TYPE HEAT EXCHANGER Filed June 21, 1967 I 5 Sheets-Sheet 5 .106Po fzbarsf, J.

INVENTOR.

A Z'Z'ORME YJ.

ABSTRACT F THE DISCLOSURE A heat exchanger including a plurality ofidentical, generally rectangular, flat flow plates. Each plate has a lipextending around its perimeter and a gasket secured to"the lippcdside ofeach plate To secure the gaskets, the platemay have a'pluralityof'spaced integral gasket keys and the gaskets have matingapertures. The gaskets haveflo w apertures which mate with the flowapertures in the plate and barriers surrounding each flow aperture.Slits' are provided in a-mating pair of barriers to permit fiewnemoneend to the-"other. The gasket is provided with fingers which=form atortuous path from one end of the plate to-the other end.

. Background of the invention 'Thi's",applicationi is 'a'eontinuation-in-part of my copending applie'ation S.N. 612,220, filedJan. 27, 1967, now abandoned and entitled Plate -Type Heat Exchanger.-This invention relates to a plate-type heat exchanger. V v,

uid processes ,it is necessary to either "I u us heat orjcool oneof thefluid streams. Various types of heat'exchangersi are used for. this.Operation. One type thatis often u'sled'isthe. plate typeh'eat exchangerwhich is forrned of aj rnl'lltiplicity efiplates clamped togetherine'spacedfside-byeside relationfThe' space between the plates providesaiflowepath on each side of the plates. As a rule, a'pairL-of assa es ,1is provided for each flow stream; The ipa sagesjare arranged 'so that,alternately, one flow stream passes. throughthe passages in the, plateand. the other stream flows between, the plates. Accordingly, onestream' flowsj along the opposite side of the same plate, in,,'heatexc'hangefrelatjion. In order to obtain af' good heat exchange relation,the flow streams usually follow a' 'tortulous pathi an'd fiow'contra toeach other.

,In certain processes the -heat exchange requirements are quitestrenuous.For example, inthe continuousdistillation of sea water thelseawater feed stream which may beat a rate. of 3 m4 gallons per minute israised fromlambient temperature to approximately 200.F. Insuch'distilla'tion units efliciency'is of paramount importance and, itis very des'i'rable that all heat be properly utilized." In, such"processes there may be two heated, discharge streams audit ispreferable, that both be utilized to raise the temperature of theflcoldsea water feed stream. One of the heated streams is distillate which ispotable water' and-the other is heated-sea water. Naturally, the twoheatedstreams' cannot be combined and it is essent'ial. that they. bekept separate throughout their travel through the; heat exchanger.Moreover, in view of the corrosion:characteristicsof the teed stream,whichis sea water,}and onef ofltheLheaIedTstreams, which is heatedseawater, it is' ,"ess'ential"tha tspecial precaution be taken to avoid.'corr0sion. Ac ;IQ Cd iiigly, essential that the heat exchanger be sodesigned that there is no possibility ermineg thejs'trea s and that:Erevices and other features whic' i, 'c'ould increase-thelikelihood ofcorrosion be avoidedf ln view of the large amount of fiow involved, itises'sential' that precal'itions' be taken to prevent the blow outfotthe gasketswhich'aresandwiched between United States Patent 0 3,404,733Ratented Oct. 8, 1968 1 to cement the gasket to one side of the plates.The cementing is in many respects a time consuming task and r if'notcarefully'executed can result in gasket blowout or crevicecorrosion. While there are many. commercialtype plate heat exchangersavailable, there are no known Satisfactory commercial plate-type heatexchangers for corrosive service utilizing compound streams.

' The present invention is designed to provide a'platetype heatexchanger which utilizes compound heated streams to heat a cool feedstream, and which is so designed that gasket blowout is prevented andcorrosion minimized. Moreover, the present invention provides aplate-type heat exchanger in which the cementing of gaskets betweenplates is eliminated.

Summary of the invention The plate type heat exchanger of the presentinvention is formed of a plurality of identical, generally rectangular,flow plates having a generally flat surface except for a lip extendingaround the perimeter of a plurality of gasket keys. Each plate isprovided with spaced apertures located adjacent each longitudinal end.The apertures form pairs to provide flow paths for different flowstreams. A gasket having apertures mating with the apertures in the flowplates is secured to the lipped side of each plate. The gasket hasapertures whichmate with the gasket keys in. the plate. The lip provideslateral support for the gasket, thereby preventing blowout. The gasketkeys lock the fingers of the gasket in place and eliminate the necessityof gluing. The gasket material forms a barrier about each aperture andprovides a tortuous path from one end to the other. The tortuous pathprovides a longlength flow. path, thereby obtaining desired fiowvelocity. Slits are provided in the pair of barriers controlling one ofthe flow streams whereby one stream can fiow from an opening on one endthrough the tortuous path to-the opening atthe other end. The otherstreams flow directly through the aperture in such plate and gasket. Theplates are clamped together in side-by-side relation with the gasketproviding spacing for a flow path between plates, and gasketed passagesfor unopened flow streams. The plates are so arranged that one of theflow streams flows in one direction between; the other fiow stream whichflows in" the opposite direction. With the above construction it ispossible to arrange the heat exchanger so that one stream will be inexcellent heat exchange relation with one or more streams of a dilferenttemperature. The construction is such that the heat exchanger may be asingle pass arrangement or a multiple pass arrangement. With a multiplepass arrangement flow direction plates are used to change the directionof flow.

- While. the preferred embodiment illustrates a heat exchanger in whichthere are three separate flow streams, the invention is not so limited.The lip and gasket keys may be utilized in gasketed plate heatexchangers in which there are only two flow streams.

Brief description of the drawings 7 FIG. 1 is an isometricdiagrammaticview of a twopass plate-type heat exchanger constructed in accordancewith the present invention; FIG. 2 is an end elevation view illustratingthe clamping together of the heat exchanger shown diagrammatically inFIG. 1; FIG. 3 is a sectional view taken on lines 3-3 of FIG. 1; FIG. 4through FIG. 8 are plan views of gasketed plates utilized in theconstruction of the heat exchanger shown in FIG. 1 with FIG. 4 being themaster gasket which is utilized in all of the plates;

FIG. 5 illustrates how the'master gasket is cut for one of the flowstreams; I

FIG. 6 illustrateshow the master gasket is cut for the flow directionplates; i

FIG. 7 illustrates how the master gasket is cut for the second of theflow streams; I v

FIG. 8 illustrates how the master gasket is cut for the third of theflow streams; 7

FIGS. 5A, 7A and 8A are details of FIGS. 5, 7 and 8 to more clearlyillustrate the slitting of the barrier of the gasket;

FIG. 9 is a sectional view taken along lines 9-9 of FIG. 4;

FIG. 10 is a plan view of a flow plate showing the location of gasketkeys;

FIG. 11 is a sectional view taken along lines 1010 of FIG. 10 showingthe gasket key; and

FIG. 12 is an enlarged plan view of a portion of the plate illustratedin FIG. 10 illustrating the positioning of gasket keys around theapertures.

Description of the preferred embodiment Referring now to the drawings,it can be seen that the plate-type heat exchanger of the presentinvention is formed from a multiplicity of plates 10 which are disposedtogether in side-by-side relation. Interposed between the plates 10 aregaskets 12 which separate the plates 10 and provide space for a flowpath between adjacent plates 10, as will be explained subsequently. Theheat exchanger is so designed that all of the flow plates 10 areidentical in construction and the gaskets 12 which are secured to oneside of the fiow plates 10 are formed from a common master gasket. Suchdesign lends itself to economical manufacture and repair.

The preferred embodiment chosen to illustrate the invention is atwo-pass exchanger and a flow direction plate 16 is disposed at themidsection to change the direction of flow. However, the same type ofconstruction may be utilized to form a single-pass heat exchanger or amore multiple pass heat exchanger, in which case a flow direction plate16 would be located at each level where it is desired to change thedirection of flow.

Referring now to the plates10 which are shown in more detail in FIGS. 4through 8, it can be seen that the flow plates 10 are generallyrectangular and are fiat except for a downtumed lip 18 which surroundsthe perimeter of the plate 10, see FIG. 9. If the heat exchanger is tobe used in corrosive service such as in a sea water distillationprocess, the plates 10 may be formed from a noncorrosive material suchas 90/ 10 copper-nickel or other similar material. All of the flowplates 10 are provided with three spaced passages 20, 22, 24 adjacenteach longitudinal end. An aperture at one end is paired with an apertureat the other end for each flow stream.

A master gasket 12 having apertures 28, 30, 32 which mate with thepassages 20, 22, 24 of the flow plate 10 is secured to the, lip side ofeach flow plate 10. The lip 18 provides lateral support for the gasket12 preventing gasket blowout due to the pressure of the flow through theheat exchanger. The master gasket 12 has barriers 34, 36, 38 about eachaperture 28, 30, 32. Between the barriers on the two ends the gasket hasa'plurality of fingers which form a tortuous path 40 ,from one end ofthe gasket 12 to the other. The tortuous path 40 provides a long-lengthflow passage thereby providing the desired flow velocity. The heatexchanger is so designed that a plate 10 having a master gasket 12secured thereto is used throughout. Therefore, if perchance one of theplates becomes damaged it is only necessary to obtain a master plate andgasket 'to repair the' heat exchanger.

As can be seen from an examination of FIGS. 5 through 7, the gasketedplates are provided with slits 42 in a pair of barriers to permit thefiow stream from one of the apertures to flow along the surface of theplate through the tortuous path 40.- For example, in FIG. 5 there areslits 42 inbarriers 36-36 which surround apertures 3 0 30. Therefore,the stream flowing through passage 22 in the plate can. flow frontpassage 22 on one end of the plate 10 through the tortuous path 40 tothe passage 22 at the other end ofthe plate 10. The plates 10controlling the-otherfiow streams are similarly provided with slits, 42.which likewise open flow, for one ofthestreams sosthatsuch stream .canflow through the tortuous path 40'al0ng the surface of the plate 10.While the gasket 12 may be cemented or vulcanized to the lipped side. ofeach, flow plate 10, cementing is a tedious process and to preventcrevice corrosion care must be taken to see-that there is no, cementextending past the edges of the gasket material. If cementing is notcarried out properly, a finger may become dislodged blocking flowthroughthe gasketed area. Accordingly, it has been found that for manyinstallations it is preferable to provide the flow plates with aplurality of integral gasket keys13 which are formed in the plate10 bystamping, see FIGS. 10-12. In such case, the gasket 12 is .provided withapertures 15 which cooperate with the gasket keys 13 to lock the gasketin position. With such construction it is not necessary tocement orvulcanize the gasket 12 to the flow plates-10. It has been found that,whereas cemented gaskets may blow out at 35-40 p.s.i. gaskets secured bygasket keys 13 and lip 18 will withstand p.s.i. The keys 13 andapertures 15 are so positioned on the plate and gasket that each fingeris provided with proper lateral support. Keys and apertures are alsoprovided about the barrier surrounding thev flow apertures, see FIG. 11.

In order to have'a two-pass heat exchanger, flow direction plate 16 isinterposed in the midsection of the heat exchanger. The flow directionplate 16 has openings 44, 46, 48 only at one end with the other endremaining solid. The solid end of the flow direction plate 16 arrestsflow through the gasketed passages and causes the flow stream to flowthrough the flow paths between the plates 10 from one side of the heatexchanger to the other. A master gasket 12 is secured to the fiowdirection plate 16. To utilize the heat transfer surface of the flowdirection plate 16, one pair of barriers are provided with slits 42. Ifmore passes are'desired, the heat exchanger may 'be provided withadditional flow direction plates.

As can be seen from FIG. 1, the plates 10 are positioned together inside-by-side relation with a gasketed plate controlling the first flowstream alternating with gasketed plates controlling the other two flowstreams. For example, in FIG. 1 it can be seen that the feed streamwhich may be a cold sea water feed stream to be heated by the two heateddischarge streams is positioned between the blow-down stream and thedistillate stream. The gasketed plates controlling the feed stream arelabelled F and gasketed plates controlling the discharge streams arelabelled B and D. Therefore, thefeed stream is in heat exchange relationwith the two heated streams in counterflow relation. It has been foundpossible to raise the temperature of a cold sea water feed stream fromambient temperature to approximately 200 F. at the rate of 3 to 4gallons per minute in a two-pass heat exchanger con- 'structed inaccordance with the present invention.

In addition to the flow plates 10, gaskets 12 and flow direction plate16, the completed heat exchanger has two covers 50 and 52. Cover 50 ispositioned on the top of the stacked assembly of plates 10 which isshown in FIG. 1 and cover 52 on the bottom of the assembly, vsee FIG. 2.The covers 50 and 52 and the plates 10 have a plurality of alignmentholes 54 and alignment rods 56 are run through the alignment holes 54.The rods 56 have threaded portions 58 on each endand nuts 60 arethreaded thereon to compress the stacked plates 10. In order to assureproper alignment, it may be desirable to. havea close fit between therods 56 and the alignment. holes 54. Care should be taken to see thatall the plates 10-are brought down evenly so that there is no bendingordeformation of any of the plates 10 in order thatthere' can bean evencompression throughout to prevent any po'ssible le'akage. The gaskets IZ-are, ;secu-red to the botton 'side of each plate,10. The gaskets arealso in contact..wi th the-'top surface of the m te-1m ndernea t easket-.- -s s assembly should be compressed sufficiently so that thereis no leakage in the assembly.- r

Welded to the top plate 2 and bottom plate ,64 are the inlet nozzles '66and outletjno'z zle's 68. The top and bottom plates 62 and 64are'similar to the remaining flow plates except that there'a'rer'1o'apertures, on one end of these plates as can be seen in FIG l.There is one ,pair of nozzles for each'fl'ow stream. The nozzles 66-68extend through openings inthe covers 50-52. As can be seen, on the topthere are the inlets 66 for the two heated streams and the outlet 68 forcold feed stream. On the bottom side there are the outlets 68 for thetwo heated streams and the inlet 66 for the cold feed stream. As can beseen, all of the outlets and inlets are located on the same side of theheat exchanger. Also, as mentioned previously, there are no passages inone end of the flow direction plate 16 and the blank end is in line withthe inlet and outlet nozzles 66-68. Since the gaskets 12 are attached tothe bottom side of each plate 10, is is not necessary to have a gasketattached to the bottom plate 64 as it is merely used as a closure forthe first flow space. The top plate 62 is provided with its regulargasket.

Accordingly, the two heated streams flow into the heat exchanger throughinlet nozzles 66 and then flow downwardly through their respectivepassages in the plates 10 until they contact the blank wall of the flowdirection plate 16. The streams then flow out through the slits 42 intheir respective barriers and flow along hte tortuous path 40 betweenthe plates to the other side of the heat exchanger, see FIG. 1. At theother side, the flow streams reform and flow through respective passagesin the plates 10, through the flow direction plate until they strike thebottom cover where flow is again arrested and the two streams againspread out, flowing back through the tortuous path 40 to the other sideof the heat exchanger, where they reform and flow through theirrespective passages in the plates 10 and thence out the outlets 68. Inthe meantime, the feed stream comes in from the opposite direction andfollows the same course of action, flowing down through the passageformed# by the openings until flow is arrested by the wall of the flowdirection plate 16, at which time it spreads out through the slits 42 inthe barriers and flows between the plates 10. As can be seen, the heatexchanger is so arranged that the feed stream flow's between the twoheated streams. Also, as can be seen, the path of the streams is atortuous path provided by the gasket and, therefore, there is goodcontact for a good heat exchange relation between the streams.

While the preferred embodiment of the heat exchanger has been shownarranged as a two-pass exchanger, the principle of the invention mayalso be used in a one-pass heat exchanger or a more multiple pass heatexchanger, and arrangements of plates other than that shown may be used.While the construction is such that a stream of one temperature may beplaced in heat exchange relation with two separate and different flowstreams of another temperature, the principle of the invention may beutilized in heat exchangers having only two flow streams.

From the foregoing it will be seen that this invention is one welladapted to attain all of the ends and objects hereinabove set forth,together with other advantages which are obvious and which are inherentto the apparatus.

It will be understood that certain features and subcombinations are ofutility and may be employed without reference to other features andsubcombinations. This is contemplated by and is within the scope of theclaims.

As many possible embodiments may be made of the invention withoutdeparting from the scope thereof, it is to be. understood that.allmatter herein set forth or shown in the accompanying drawings is tobe interpreted as illustrative andnot in a limiting sense.

1. A plate=typeheat exchanger comprising a plurality of identical platesand'initially identical gaskets, [each plate being substantially flatexcept fora lip extending around the perimeter and having at least .two'spaced apertures adjacent each longitudinal end, an "aperture at oneen'dbeing paired with'an" aperture at the other end, a gasket secured to thelipped side of the plate with the lip providing edge 'support'for thegasket, each gasket having apertures mating'with the 'apertures in theplates and having a barrier about each gasket aperture, the barrierabout a mating pair of gasket apertures being at least partially removedto provide a path from one of said gasket apertures at one end of theplate to its paired aperture at the other end of the plate, the platesbeing clamped together in side-by-side relation with the gasketsproviding a space between adjacent plates whereby fluid from a matingpair of apertures may flow between adjacent plates, remaining aperturesin the plates and the gaskets providing a gasketed passage for theunopened flow stream, and inlet and outlet nozzles for each flow stream.

2. The heat exchanger specified in claim 1 wherein the flow plates areprovided with a plurality of integral gasket keys and the gaskets areprovided with key apertures cooperating with the gasket keys to securethe gasket to the plate.

3. The heat exchanger specified in claim 2 wherein fingers extend fromopposite longitudinal edges of the gasket on an alternate basis to forma tortuous path for the flow stream from one end of the plate to theother whereby the flow on one side of a plate is in counteropposition tothe flow on the other side.

4. The heat exchanger specified in claim 3 include a flow directionplate having apertures at only one end to change the direction of flowand thereby repass the fluids past each other again in heat exchangerelation.

5. The heat exchanger specified in claim 3 wherein there are three flowstreams, one of a first temperature and two different flow streams ofother temperatures and the plates are so arranged that one flow streamis sandwiched between the other two flow streams.

6. In a plate-type heat exchanger in which a feed stream of a firsttemperature is passed in heat exchange relation with a.- stream of asecond temperature comprising a plurality of identical flow plates, eachof said plates being substantially flat except for a plurality ofintegral gasket keys spaced about the surface of the plate, said plateshaving at least two sets of apertures, said sets of apertures beingspaced from each other and one aperture from one set being paired withan aperture from the other set; a gasket secured to the keyed side ofeach plate, each gasket being initially identical and having apertureswhich mate with the apertures in the plate and a barrier which surroundseach gasket aperture, the gasket also having a plurality of fingers toform a tortuous flow past from one set of apertures to the other and aplurality of key apertures which cooperate with the gasket keys tosecure the gasket to the plate, the gasketed plates being clampedtogether in side-bysicle relation, at least a portion of a pair of thebarriers in each gasket being removed thereby opening the gasketedpassage formed by the mating apertures in the plates and the gaskets sothat such stream can flow through the tortuous gasketed path between theplates from an aperture at one end to its mating aperture at the otherend.

7. The heat exchanger specified in claim 6 wherein the plates areprovided with peripheral lips to provide additional lateral support forsecuring the gasket.

8. The heat exchanger specified in claim 6 wherein there are three flowstreams, one of a first temperature and two different flow streams ofanother temperature and the plates are so arranged that the first flowstream is sandwiched between the other two flow streams.

9. The heat exchanger specified in claim 6, wherein the fingers formingthe tortuous flow path extend inward from opposite sides of the gasketson an alternate basis so that the flow on one side of a plate iscountercurrent to the flow on the other side of the plate.

10. The heat exchanger specified in claim 6, wherein slits are made inthe barrier to form the flow path and the portion of the barrierremaining has key apertures to cooper-ate with the gasket keys to securesaid portion of the gasket to the plate.

References Cited 1,890,108 12/1932 Chatain 165%166XR 2,248,933 7/1941AStle "165 -167 2,777,674 1/1957 Wakeman 165-5161 FOREIGN PATENTS 57,169 1/1940 Denmark.

995,395 8/1951 France.

835,007 3/1952 Germany.

ROBERT A. OLEARY, Primary Examiner.

M. A. ANTONAKAS, Assistant Examiner.

